The focus of this research is on the role which behavioral stress may play in the etiology of essential hypertension. Some studies of early or borderline hypertension suggest that elevations of heart rate and cardiac performance resulting from excessive beta-adrenergic drive on the myocardium may sometimes represent an early stage in the development of hypertension. Previous research in our laboratory has shown that exposure to a stressful shock-avoidance task providing a strong incentive for active coping can evoke a temporary state similar to borderline hypertension, involving large increases in heart rate, systolic blood pressure and indirect measures of cardiac performance mediated by beta-adrenergic mechanisms. The intent of this research is to provide evidence concerning whether excessive beta-adrenergic reactivity to stress may be predictive of high risk of later hypertension. The proposed research will examine: 1) whether naturalistic incentives for active coping (e.g. monetary rewards, competition with peers, evaluation by others) are as effective as shock in enhancing sympathetically-mediated changes in blood pressure and myocardial performance; 2) whether high beta-adrenergic reactivity to stress is associated with increased incidence of hypertension among parents and other relatives, or with personality traits such as suppressed hostility or Type A characteristics; 3) whether high reactivity in the laboratory is associated with reactivity to real-life stresses, such as taking course examinations.